UA123564C2 - Heat-treated pvc-plastic panel - Google Patents

Abstract

The invention relates to a method for treating PVC plates and to plates and panels produced therefrom. The invention also relates to a plates and panels, in particular wall, ceiling or floor panels comprising a heat-treated support panel (12) based on polyvinyl chloride having a density of, in particular 900 bis 2.500 kg/m3 and a film (17) secured thereto. The film is a thin PCV film and comprises a printed decorative pattern (18) applied thereto.

Description

1. The field of technology to which this invention belongs

The present invention relates to a method of processing PVC panels and, namely, an improved panel, in particular, a wall, ceiling or floor panel based on a carrier plate made of solid PVC (NPVXUH), as well as a method of its manufacture. 2. Level of technology

Polyvinyl chloride (PVC) has long been used in the production of floor coverings. It is a thermoplastic material, which without the addition of auxiliary substances is hard and brittle. However, the mechanical properties of PVC can usually be adjusted in a wide range by adding appropriate auxiliary substances (additives) to it, such as plasticizers, fillers, dyes, stabilizers, etc. In this regard, the term "PVC" used herein does not refer to pure polyvinyl chloride, but to PVC with additives that are usually added and are necessary to make this material suitable for use in various industries in practice, unless otherwise required.

A typical example of known technical solutions is publication OE 10 2006 058 655 A1. This document describes a floor panel in the form of a multi-layer rectangular laminate, which had a supporting plate of soft polyvinyl chloride and a decorative paper layer superimposed on the polyvinyl chloride layer. But the use of decorative paper canvas is technically difficult and associated with significant costs.

From the publication OE 10 2006 029 963 A1 is a known PVC floor covering made of polyvinyl chloride, on which a strong lacquer layer was applied to increase the durability of the floor covering. The varnish layer, the basis of which is acrylate resin, was treated by irradiation. The essence of this invention was that in order to give the flooring antistatic and/or conductive properties, conductive substances were added to the acrylate resin.

The same applicant proposed further improvement of the aforementioned lacquer coating UMO 2008/061791 JSC. The contents of this document in its entirety are incorporated herein by reference. The essence of the proposed improvement was that two different liquid polymer layers were applied to the surface of the panel in a "wet-on-wet" manner, between which, thus, partial mutual mixing of their materials took place. Next, these two layers, superimposed on each other in the wet state, were subjected to hardening, and the coating formed as a result of this partial mixing received a gradient of hardness, such that the hardness of the coating decreased in the depth of the coating from its surface.

EP 3 088 205 A1 relates to a method of manufacturing a decorative panel for a wall or floor manufactured according to such a method.

Publication MO 2011/1141 849 A1 relates to a panel of the type containing at least one base and a top layer provided thereon, and the top layer contains a pattern. The base consists mainly of foamed plastic.

Publication OE 10 2010 011 602 A1 relates to a method in which the carrier plate is first laminated on one side or on both sides with a plastic film. A laminated carrier plate is fed to the printer and images or graphics are printed onto the plate, whereupon the ink is then cured using UV radiation. The printed plate is then removed from the printer and temporarily stored on the shelves for further processing. The printed carrier plate is then coated with a single-layer or multi-layer varnish, which hardens under

UV irradiation.

Publication RK 2 805 548 Ai relates to a method of manufacturing a non-slip floor covering comprising a main structure of plasticized PVC reinforced or not reinforced with a textile base and associated with a surface coating which is embedded particles that provide a structure with non-slip properties.

The main problem with PVC sheets, and therefore with panels or floors made from them, is that they are less resistant to high thermal loads, such as solar radiation.

For example, PVC panels are deformed and bent under the influence of intense direct solar radiation. This can happen, for example, when the panels are used as a floor covering in a room with large windows, such as a conservatory.

Deformation or bending of PVC panels can also be caused by other heat sources, such as heating radiators, which limits the use of such panels, for example, in residential premises.

Thus, in connection with the above-mentioned disadvantages of known PVC panels, the task of this invention was to create a method of processing PVC plates that would allow to increase the stability of plates known from the state of the art. In particular, the purpose of this invention is to create a method of processing PVC panels, with the help of which it would be possible to increase the resistance of the panels in relation to solar radiation and thermal load. It is also an object of the present invention to provide an improved panel, in particular a wall, ceiling or floor panel, containing a carrier plate (in particular) of rigid PVC. In addition, the purpose of this invention is to create such a panel that would have increased durability and high quality decorative patterns.

These and other tasks, which are considered in this description or which may already be known to specialists in this field, find a solution in the method of processing the PVC plate according to item 1, in the panel according to item 9 and in the method of manufacturing both according to p. 25 Formulas of the invention. 3. Detailed description of the invention

The present invention relates to a method of processing a polyvinyl chloride (PVC) plate, which includes the following stages in the specified order: feeding the PVC plate; heating a PVC plate in a thermal chamber to 70 "C and cooling the heated plate. Thus, this method relates to heat treatment of PVC plates. Quite unexpectedly, it was found that such heat treatment allows to significantly improve the strength of known PVC plates, in particular, with respect to thermal loads and/or solar irradiation. It is believed that heating the plates to the glass transition temperature and, even better, leads to a reduction in internal stresses in them. To achieve this result, the plates should be heated to at least 70 "C, since this temperature is close to the glass transition temperature of ordinary PVC plates and, in particular, rigid PVC plates. Although the physical and chemical relationships in these materials are not fully elucidated, it is believed that as a result of heating and subsequent cooling, the reorientation of macromolecules occurs in them, which leads to a decrease in internal stresses and, ultimately, to an increase in the stability of the plate. In particular, the processing of the PVC plate by the method according to the present invention makes it possible to effectively reduce or even reverse the bending and general deformation of the PVC plate exposed, for example, to strong exposure to direct sunlight. Processed according to 3 of the present invention can, among other things, polyvinyl chloride plates, which are otherwise not amenable to processing, such as, for example, plates formed by extrusion. However, the proposed method can later be applied to panels that have PVC plates as supporting elements, possibly with coating layers applied to them. Such panels will be discussed in more detail below in the examples of implementation of this invention.

In a preferred embodiment, the plate is heated to at least the glass transition temperature, more preferably to a temperature of at least 75°C, even more preferably to a temperature of at least 79°C, even more preferably to a temperature of at least 81°C, and even more preferably to a temperature of at least 85°C.

The glass transition temperature of PVC is approximately 80 "C and may be slightly lower or higher depending on the additives used. For the purposes of this invention, it is desirable to heat to a slightly elevated temperature, i.e. several degrees above the glass transition temperature of the processed PVC. At the same time, it is desirable that the PVC plate completely warmed up to the desired temperature, that is, so that the core of the plate had the minimum temperature of the desired interval.

However, due to the low thermal conductivity of PVC, it may take a relatively long time to warm up the core of the plate, that is, to bring it to the desired temperature, for example, its deepest part. In this regard, when extruding a plate, it is desirable to use thermal energy, and not to allow the plate to cool completely after extrusion. To prevent this, the plate is allowed to cool only to 40-50"C, and then heated in a thermal chamber above the glass transition temperature. This should ensure uniform heating of the entire volume of the plate.

In this way, in particular, the stability of the dimensions of the plates is achieved.

In the best version, the plate is maintained at a minimum temperature for at least 3 minutes, even better - for 5 minutes, and best - for at least 10 minutes. It has been found that the internal stresses of the plate or the desired effects according to the invention can be most assuredly achieved if the plate is held at the desired minimum temperature for some time before it is cooled again.

In addition, it is desirable that the plate heats up at an average rate of 2 "C/min. to 20 "C/min., preferably - an average of 4"/min. to 15"7/min.; better - on average from 6"/min. to 127/min. and best - on average from 7"/min. up to 10"/min. Due to the relatively low thermal conductivity of PVC, slow heating is preferable, as otherwise the outer parts of the plate may heat up to a temperature well above the desired minimum temperature, while the inner part of the plate will remain is still relatively cold. Thus, slow heating in certain areas makes it possible to make the heating uniform and thus to reorient the molecules more evenly or give them a new orientation (as far as one can imagine, considering that the exact mechanism of the effect of heating on the alignment of the molecules is still not fully known).

It is believed that such uniformity is decisive for obtaining especially good properties of such slowly heated plates. So, for example, at a heating rate of 1"/min. the plate heats up for one hour by approximately 60 "C. At the beginning of this process, the heating occurs due to the large difference between the temperature of the still cold plate and the temperature of the thermal chamber, and depending on the used thermal chamber and the type of heating, it can take place faster than at the end of the process. Thus, the heating rate may be greater at the beginning of the heating process than at the end of the process, although this factor can be minimized by selecting a suitable thermal chamber or its controls. Therefore, the values of the heating rate specified in this description should be considered its average values, so that, for example, the expression "speed 2"/min" means that it takes approximately 40 minutes to heat the plate from 20 "C to 1007. In this case, it is also sufficient that most of the mass of the plate is brought to the desired temperature, for example, 90 9b (mass), although, in general, it is still desirable that the entire plate is heated.

No less important than the heating of the plate is the process of its cooling. With rapid and uneven cooling (for example, sharp immersion in a water bath at room temperature), despite preliminary heating, only a slight or even no improvement in stability can be observed. To achieve improvement, the plate should be cooled slowly and evenly, at least to 50-40 "C. Slow cooling to room temperature is more acceptable. However, a significant improvement in stability is also observed when the plate is immersed in a water bath after reaching a temperature of 50 "C, but the water bath should have a temperature not lower than 35-25 "C (depending on the starting temperature of the immersed plate; the temperature difference between the plate and the water bath should not be too great).

Next, it is proposed to cool the plate under control in a refrigerating chamber so that the cooling takes place uniformly on the surface to a minimum temperature of 30-50 C in the core of the plate with a cooling rate on average from 3"/min to 20"/min, in the best option - from 5"/min. to 157/min., in an even better case - from 7"/min. up to 12"/min. and in the best case - on average from 8"/min. up to 10"/min. It should be remembered that the values of the cooling rate indicated here, as well as for the heating rate, represent average values until the temperature of the core of the plate reaches approximately 30-50 "C, that is, for example, only by 10 degrees above ambient temperature. Slow and controlled cooling makes it possible to obtain particularly stable plates. At the same time, it is believed that slow cooling gives a good fixation of the orientation of the molecules.

In the best version, the PVC plate is fed through the thermal chamber to the conveyor, and the thermal chamber is a continuous flow thermal chamber. Heating and/or cooling in such a continuous process is particularly economical, since different thermal zones with different temperatures can be arranged in a continuous thermal chamber. So, for example, the temperature in the chamber in the direction of transportation can be constantly increased or decreased, thanks to which uniform rates of heating or cooling processes can be realized.

In the best version, the process of cooling the heated plate is carried out in a chamber of continuous action. In this process, it is also possible to provide different temperature ranges along the direction of transport of the wafers through the thermal chamber and thus maintain as uniform a cooling rate as possible and, for example, an approximately constant temperature difference between the wafer and the chamber environment. At the same time, the temperature in the refrigerating chamber decreases along the direction of transport of the plate through it. When the plate leaves the chamber, it is preferably at a temperature close to the ambient temperature, ie, for example, only 10 "C or 20 "C above the ambient temperature.

The present invention also provides a panel that includes a plate (in this description, the terms "plate" and "carrying plate" are used interchangeably in the following) of polyvinyl chloride, which is preferably processed according to the methods discussed above. A PVC film with a thickness of 0.04-0.2 mm is attached to this plate, which has a decorative pattern printed directly on it, and a hardened polymer layer is placed on top of this film. The polymer layer, as a rule, is created mainly on the basis of polymerizable resin, in particular, acrylate resin. As a rule, the hardened polymer layer has a hardness gradient described in the above-mentioned document UMO 2008/061791 of the same applicant.

The heat treatment of the PVC plate is preferably carried out after applying the film

(mainly PVC films). Printing of the decor and application of subsequent layers is mainly carried out after heat treatment of the PVC plate with the PVC film applied to it.

Polyvinyl chloride sheet consists mainly of rigid PVC (known by the abbreviated name NIVH) and thus contains little or no plasticizers. This applies to all methods and products described here.

In contrast to the above-mentioned prior art ЮОЕ 10 2006 058 655 A1, this invention offers a panel that does not require a separate decorative paper, since the decorative pattern is printed directly on the PVC film. PVC film gives the advantage that it allows you to abandon costly pre-treatments of the carrier plate (although, of course, pre-treatment can be carried out if necessary). In particular, the use of PVC film in the body of the panel according to the present invention also allows you to abandon the costly process of grinding the surface of the carrier plate and applying putty and primer - operations that were usually necessary in this field of technology.

In one of the best embodiments of the invention, the polymer layer has a hardness gradient such that its hardness significantly and continuously decreases deep into the layer from its surface. The layer, which has a hardness gradient, effectively interacts with the relatively soft PVC film and acquires, among other things, good sound insulation properties.

In a preferred embodiment, the printing ink used to print the decorative pattern contains a solvent and preferably a UV printing ink. Such paints easily dissolve the surface of the PVC film, thanks to which a strong fixation of the paint on the film is ensured. When using UV printing ink, a very strong cross-linking of the ink with the surface of the PVC film is also formed. Thus, the UV-curable printing ink is particularly suitable for these purposes, as it contains chemically active agents that are subsequently organically incorporated into the lattice of the structure, for example, M-vinylcaprolactam.

In the best option, a polymerizable printing ink is used for printing a decorative pattern, in particular, based on polymerizable acrylate resins and/or M-vinylcaprolactam (liquid chemically active solvent) produced by the company

WELCOME The authors quite unexpectedly discovered that it is possible to improve the adhesive properties of a set of layers if, instead of ordinary water-based emulsion paints

Do not use printing inks capable of polymerization. This is especially true of the advantages of a structure with a polymer layer and, in particular, one that has a hardness gradient. Acceptable amounts of polymerizable acrylate and M-vinylcaprolactam in the printing ink turned out to be in the range from 2 to 50 9o (wt.), better - from 5 to 40 9bwt., and best - from 10 to 30 9o (wt. ). These numbers represent the total amount of acrylate and M-vinylcaprolactam. An appropriate mass fraction of M-vinylcaprolactam in printing ink is, for example, from 3 to 12 95.

The positive effect of this invention is demonstrated especially clearly when the printing ink of the decorative layer (i.e. the decorative pattern) and the polymer layer solidify together (when printed directly, for example, by digital printing, the decorative layer consists as if of printing ink). Curing of a polymer layer or polymerizable printing ink (for example, polymerizable acrylates or generally chemically active UV inks) here refers to a chemical reaction occurring during polymerization. Co-hardening (co-polymerization) of the polymerizable components (acrylate systems and/or M-vinylcaprolactam) of the printing ink and the polymer layer is completed by chemical cross-linking at the boundary of the two layers, which is considered responsible for improving the adhesion of the layers.

Polymerizable components, which are preferably used in this invention, include as main components acrylates, in particular, acrylate monomers, oligomers and optionally photoinitiators, as well as a liquid active solvent, M-vinylcaprolactam. M-vinylcaprolactam can be added to printing ink in addition to acrylates as a solvent and polymerized together with them. Alternatively, you can do without acrylates and provide a correspondingly larger amount of M-vinylcaprolactam, since /M-vinylcaprolactam itself can be polymerized. A specialist in this area can learn more about this issue in the German publication OE 197 02 476 A1. Thus, in the best embodiments of the invention, the polymerizable part consists essentially entirely of

M-vinylcaprolactam. Photoinitiators as an irradiation factor cause the polymerization of monomers or oligomers, which contributes to the rapid hardening of printing ink.

In the best version, the PVC film has a thickness of 0.05 to 0.15 mm, and in an even better version - 0.06 to 0.095 mm. Films of this thickness are very easy to process, and a calender can be used to apply them. In particular, for example, a PVC film can be applied directly using a heated calender so that the film is melted and thermally bonded to the carrier plate. In this case, there is no need to use additional glue to fix the film on the carrier plate, although this is possible as an alternative or additional option.

Preferably, the polyvinyl chloride sheet has a density of 900 to 2500 kg/m, preferably 1000 to 2200 kg/m3, more preferably 1300 to 1950 kg/m, and most preferably 1350 to 1500 kg/m. Plates of this density are very strong and resistant to external influences and are especially suitable for use in floor coverings. In addition, these plates allow you to form fixing or connecting elements on their side edges, for example, to combine these plates with each other in a continuous flooring.

It was established that the best thickness for a PVC plate (or carrier plate) is in the range from 3 to 20 mm, even better - in the range from 4 to 15 mm, even better - in the range from 3 to 12 mm, and the best - in intervals from 4 to 10 mm. It turned out that the bearing plates of this thickness are sufficiently stable in the process of their manufacture, and also provide a sufficiently high absorption of the noise of steps when walking (in floor coverings) and the stability of the dimensions of the finished panel.

In the best embodiment of the invention, a layer including a UV primer is applied to the PVC film. This layer has a surface mass from 1 to 20 g/m", in the best version - from 2 to 15 g/m", and in the best - from 2 to 5 g/m". Dipropylene glycol diacrylate in the amount of , for example, 2 g/m", which provides a good effect. The primer is applied mainly to the printing ink, thus improving the adhesion between the printing ink, the base and the polymer layer. It was found that the improvement of adhesion with the help of primer is especially noticeable in places with a small amount of printing ink.

In general, extruded PVC sheet is preferred.

In one of the best embodiments of the invention, small particles resistant to abrasion, in particular, corundum particles with an average diameter of 10 to 100 μm, preferably from 20 to 80 μm, preferably from 25 to 70 μm, and especially good -- from 30 to 60 microns. Due to the abrasion resistance of such particles, the service life of the panel according to the present invention can be significantly increased.

From In one of the best variants of the invention, a decorative pattern applied to

PVC film directly by digital printing is the only decorative layer in the panel according to the invention, i.e. the proposed panel does not contain any other decorative papers or decorative films. This eliminates the need to add any papers for decoration and other similar purposes and allows to significantly reduce production costs and simplify the process of manufacturing the panel according to the invention.

As mentioned above, in the best embodiment of the invention, the printing ink of the decorative layer (decorative pattern) hardens (polymerizes) together with the polymer layer applied to it, preferably by their joint irradiation. As a result, partial chemical cross-linking of the used polymers takes place in the boundary layer between the printing ink and the polymer layer (layers) applied to it. As it turned out, in this case, particularly good adhesion of the polymer layer to the carrier plate can be achieved.

The present invention, in addition, offers a method of manufacturing a panel, in particular a wall, ceiling or floor panel. According to this method, at the first stage, a plate (carrier plate) made of polyvinyl chloride is fed, which is processed mainly by one of the methods described above (heat treatment/annealing). The plate has a density in the range from 900 to 2500 kg/m3. Alternatively, an untreated PVC plate is used, which is subjected to the above-described heat treatment later, for example, after certain initial or all subsequent layers have been applied to it. A PVC film with a thickness of 0.04 to 0.2 mm is created on this carrier plate, preferably with the help of a calender, and then heat treated. After heat treatment, a decorative pattern is printed on the PVC film. After printing the decorative pattern on the PVC film, the first liquid polymer layer is applied to the soil layer. At the next stage, the polymer layer hardens, preferably together with the printing ink. If necessary, at least one second polymer layer in a liquid state can be applied to the still wet first polymer layer in such a way that the materials are partially mixed between them. Curing of the printing ink and the polymer layer(s) can be carried out in one stage of the process or sequentially in two separate stages of the process. The curing of the polymer layer refers to the chemical reaction that occurs during polymerization. The hardening process differs from the drying process of such layers in that the drying process only reduces the water content in them or completely removes it.

In a preferred embodiment, the first and second polymer layers are applied in such a way that the cured polymer layer receives a certain hardness gradient, such that the hardness of the coating decreases with depth from the surface of the created coating. Since this process is described in detail in the aforementioned document UMO 2008/061791 JSC, its further details are omitted here.

In the best version, a heated calender is used in such a way that the PVC film is welded to the carrier layer under the influence of heat. This allows the application of the film and its fixation to be carried out easily and safely in one stage.

In one of the best options, a directly printed decorative pattern imitates the surface of a covering made of wood, stone or tile. PVC film is usually smooth or white.

This provides a good background color for most commercially used decor types.

Below, the advantages of this invention will be explained in more detail using two non-limiting examples.

Sample example: "Panel with conventional indirect gravure printing"

A layer of primer based on a commercially available aqueous acrylate dispersion is first applied to a 4 mm thick PVC carrier plate using a roller application unit.

At the next stage, the supporting PVC plate is smoothed using a roller applicator with putty mastic based on a highly saturated aqueous acrylate dispersion.

Next, a primer for printing based on an aqueous acrylate dispersion mixed with fillers and color pigments is applied by pouring. After each of these stages of creating a coating, intermediate drying takes place at a temperature from 80 to 200 "C. The carrier PVC plates treated in this way are fed to the printing press, which usually consists of a corrugated roller (corrugated cylinder) and a rubber roller for transferring the printed pattern from a fluted cylinder to a plate.The printed pattern is formed by three lower printing devices in this technological chain, where each printing machine applies its own printing ink containing colored pigments and an aqueous acrylate dispersion.

For example, to simulate dark walnut wood, is 5 g/m applied? printing ink.

Next, a commercial UV primer is applied to the layer of printing ink with a roller applicator. And finally, to create a polymer layer with a hardness gradient, a polymer layer is applied as described in UMO 2008/061791.

From Example. A panel where the pattern is printed on a PVC film.

A 0.03 mm thick PVC film was applied to a b mm thick PVC carrier plate made of rigid PVC using a heated calender so that the film was welded to this carrier plate under heat. The plate treated in this way was subjected to intermediate cooling to 30-50 "C in accordance with the best method of heat treatment described above.

The PVC film welded in this way was applied with a digital printer with the same decorative pattern as in Example 1. However, this process used a digital printing ink that contained a solvent and was polymerized under ultraviolet radiation. Approximately 2 g/m" of paint was required to create the printed pattern.

The color was first fixed by irradiation with an intensity of 150 mJ/cm: (mercury). After that, the first layer capable of hardening under UV irradiation was applied in an amount of 2 g/m, containing mainly dipropylene glycol diacrylate. An oligomer containing double bonds and photoinitiators was applied to this non-irradiated layer. Next, this composition was exposed to irradiation from a UV light source, due to as a result of which the polymerization of its respective components took place.

The resulting polymer layer contained the printing ink and all layers applied to it. 4. Description of the best variants of the invention

The present invention is described in more detail below with reference to the drawing figures, in which: in Fig. and schematically shown installation for heat treatment of PVC plate; in Fig. 16 schematically shows the temperature profile of the installation; in Fig. 2 shows a schematic representation of the panel 10 with a carrier plate 12 made of polyvinyl chloride; in Fig. C schematically shows the installation for coating; and in fig. 4 schematically shows a test setup for comparing treated and untreated panels.

Figure 1 schematically shows an installation for heat treatment of a PVC plate. This installation consists, in fact, of thermal chamber 1, which in this example is a thermal chamber of continuous action. This thermal chamber has a conveyor 2, on which the processed products pass through it in the direction of arrow 3. Pos. 12 labeled PVC plates that are transported through the thermal chamber from left to right. Pos. 10 indicated ready-made panels on which the required layers or coating films have already been applied according to the description provided below as an example. Such coated panels 10 can also be subjected to heat treatment directed at their respective carrier plates 12. Thermal chamber 1 has seven zones 91-07 with different temperatures.

It is clear that the installation shown here is only one possible example, which does not exclude other options with more or fewer zones and completely different temperature profiles. Plates 12 or panels 10 enter the first zone 01 of the thermal chamber. The temperature within the first zone O1 continuously increases in the direction of transport of the chamber.

The temperature course or temperature profiles in separate areas of the chamber are shown in Fig. 1B.

The temperature is plotted on the vertical axis, and the horizontal axis is directly proportional to the length of the thermal chamber (GOhep). Dotted lines show transitions between different zones from

О1 to 07. In the given example, the temperature in zone О1 increases continuously at a relatively low speed. This is due to the fact that the panels or plates when entering the thermal chamber have a relatively low temperature, for example, room temperature, and therefore the already relatively low temperatures of the thermal chamber cause rapid heating of the plates, since the speed at which the body heats up depends mainly on the temperature difference between this body and the surrounding air. As experts in this field know, large temperature differences lead to the transfer of a greater amount of thermal energy and, therefore, to faster heating of the body. By choosing an acceptable temperature profile in the direction of transport in the thermal chamber, the time course of heating the plates can be controlled. During the treatment process, the heating or cooling should be as uniform as possible, that is, the heating or cooling gradient should be maintained as constant as possible.

In zone 02, the temperature in the direction of transportation rises higher than in zone O1. In the zone

The OZ temperature is kept at a constant level, and the plates during transportation through the O3 zone are kept at the desired temperature for several minutes. In zone 04, the temperature in the thermal chamber slowly decreases in the direction of transport, as can be seen from the relatively flat temperature graph in Fig.25. In further zones 05-07, the temperature continues to drop lower, and the panels slowly cool down to a temperature close to room temperature (for example, 30 "C or 35 "C). As shown in these graphs, the cooling phase lasts longer than the heating phase, meaning that cooling must be relatively slow. After the wafers exit the thermal chamber, they can be directed to storage or, if necessary, onto them

For further processing.

In Fig. 2 shows a panel 10 that is covered with several films and layers and can be used in a floor covering. The panel 10 has a plate (carrying plate) 12 made of PVC, which on its side edges has tongue and groove connection elements that allow the panels 10 to be connected to each other in a continuous covering. The carrier plate is made of rigid PVC (NPVC), obtained by extrusion, and, if necessary, is subjected, for example, to heat treatment by one of the methods described here.

A PVC film 17 is applied to the plate (carrier plate) 12. A decorative pattern (decorative layer) 18 is created on the upper surface of the film 17, preferably by digital printing. It can be any decorative pattern that is determined by the intended use of the panel. A polymer layer 19 is created on the PVC film with a decorative layer, which can harden under UV irradiation. The presented drawing does not correspond to the actual scale, and the layers on it are shown with separate openings for clarity.

The plate 12 is actually much thicker than the layers deposited on it, and has a thickness of the order of several millimeters, while the coating applied to it has a total thickness measured only by fractions of a millimeter.

Below with explanations on Fig. As an example, the process (method) of manufacturing a panel according to this invention is considered in detail. In Fig. C schematically shows the installation for coating the plates 12 and, thus, the production of panels 10. In this process, plates 12 of hard PVC are used, which have a thickness of 4-8 mm and were preferably subjected to the above-described preliminary heat treatment. However, in an alternative version, the heat treatment described here can be subsequently subjected to the finished panel 10 or its intermediate blank. Plates 12 are guided by a roller conveyor 21 through various settings of the coating device. The number of coating installations shown in this diagram is not exhaustive and serves only as an illustration to explain the method according to the invention. In front of, behind and between the shown installations, various other installations can be added, for example, for drying, for applying primers, for applying putty, etc. to the plates 12. The film is unwound from the feed roll 31 and is fixed by means of a heated calender cylinder 32 on the upper surface of the plate 12. The film is cut using appropriate cutting means (not shown) well known to those skilled in the art.

The installation 60 creates a decorative finish, for example, a decor under natural wood by applying a suitable pattern to the PVC film 17 using digital printing. After printing, a polymer layer is created on the installation 70 for coating.

At the same time, the polymer layer is provided with such a hardness gradient that its hardness significantly and continuously decreases with depth from its surface. For this purpose, in the first coating unit 71, the first polymer layer is created on the basis of a polymerizable acrylate composition. In block 72, another polymer layer is applied to the first polymer layer in a wet-on-wet method. The second polymer layer has, for example, a higher content of double bonds, as described in detail in the aforementioned application regarding the hardness gradient. Both polymer layers are applied in blocks 71 and 72 in a "wet-on-wet" manner, resulting in partial mixing of their materials at the border of these two layers. In installation 73, these two polymer layers are cured simultaneously under UV irradiation.

In a preferred embodiment, the installation 60 is a digital printing device that uses a polymerizable acrylate-based printing ink. Under these conditions, it is desirable that during the passage between units 60 and 70 no hardening of the ink occurs, but on the other hand, it is still better to carry out an intermediate stage of drying, during which a certain amount of moisture would be removed from the acrylate of the printing ink subject to hardening. In this case, simultaneous hardening of the printing ink, the first and second polymer layers will take place in the unit 73 for polymerization, which makes it possible to obtain a particularly stable surface.

Comparison of standard PVC with heat-treated PVC

Experimental studies were conducted on the effect of heat treatment according to the invention. For this, a supporting PVC plate was taken, which was produced using a twin-screw extruder and had a density of 2.050 kg/m3. A high-performance decorative coating was applied to this plate and a floor panel 510 was made on its basis. In this way, numerous panels were made, which were assembled into an experimental floor covering with dimensions of approximately 2 by 4 m ("standard PVC"), schematically shown in Fig. 4. For comparison, the same extruded plate was subjected to processing according to the invention in a thermal chamber, where after cooling to about 40 "C, it was again heated to 85 "C and then slowly cooled ("heat treated RMS"). The same coating was then applied to these panels, and the finished panels were placed in a second experimental deck, the same as the untreated 510 panels.

Both experimental decks were exposed to infrared radiation on an area of approximately 1 m? from above from four IR sources 501 (which simulated solar radiation through deep windows, for example, in a conservatory). The radiators heated the surfaces of floors or panels at a rate of approximately 17/min. to a surface temperature of approximately 80 "C. During irradiation, the maximum curvature of the panels was measured and recorded. The results of this test are shown in the table below.

Table 11111111 | Standard PVC) Treated PVC

On an experimental deck of non-heat treated PVC panels (standard PVC) under 501 infrared lamps, noticeable buckling began after 25 minutes at a surface temperature of 50°C. Bending took place on a large area, which in Fig. 4 is marked with circle 502. No noticeable curvature was detected on the experimental deck made of treated PVC panels. On the untreated flooring ("standard PVC"), a maximum curvature of 9.5 mm of bending was detected at a surface temperature of 68.6 "C. In the flooring made of treated

No changes were detected in PVC panels at this temperature. The tests were terminated after 127 min. and a surface temperature of 81 "С.

In the entire studied area, the floor covering made of treated PVC panels was stable and showed no signs of deformation. The maximum surface temperature during the tests corresponded to the temperatures that can be reached in practice under conditions of direct solar radiation, especially in panels with dark decor.

Problems with standard PVC regularly cause numerous complaints, in connection with which many panel manufacturers indicate on their packages that "these products are unsuitable, for example, for use in conservatories and places with direct sunlight". In contrast to them, plates processed according to the present invention do not face similar complaints.

Claims (38)

FORMULA OF THE INVENTION 1. The method of processing a plate made of polyvinyl chloride (PVC), which includes the following stages in the following order: - feeding the PVC plate, - heating the PVC plate in a thermal chamber to at least 70 "C, and the plate is heated at an average rate of 4 to 15 "C/ min - cooling of the heated plate, and the cooling is carried out in a controlled manner, namely at an average speed of 5 to 15 °C/min. 2. The method according to claim 1, which is characterized by the fact that the plate is heated to at least the glass transition temperature. 3. The method according to claim 1 or claim 2, which is characterized by the fact that the plate is maintained at a minimum temperature for at least three minutes. 4. The method according to any of the previous items, which is characterized by the fact that the plate is heated with a gradient of 6 to 12 "C/min on average. 5. The method according to any of the preceding items, which is characterized by the fact that the plate is cooled in a controlled manner in a refrigerating chamber with a cooling gradient of 7 to 12 "C/min on average. b. A method according to any one of the preceding claims, characterized in that the PVC plate is moved on a conveyor through a thermal chamber, and the thermal chamber is a continuous flow chamber. 7. The method according to any of the previous points, which is characterized by the fact that the cooling of the heated Zo plate is carried out in a continuous thermal flow chamber. 8. The method according to any of the preceding points, which is characterized by the fact that the PVC plate before heat treatment or after it is equipped with a PVC film having a thickness of 0.04 to 0.2 mm. 9. The method according to any of the previous items, characterized in that the plate (12) made of PVC has a thickness of 3 to 20 mm. 10. The method according to any of the previous items, characterized in that the PVC plate (12) is a PVC plate produced by extrusion. 11. A panel comprising a plate (12) made of polyvinyl chloride and a film (17) attached to it, characterized in that the film (17) is a PVC film with a thickness of 0.04 to 0.2 mm and has a decorative printed directly on it pattern (18), and a hardened polymer layer (19) is provided on top of this PVC film. 12. The panel according to claim 11, characterized in that the polymer layer (19) has a hardness gradient such that the hardness of this polymer layer decreases from its surface into the layer essentially continuously. 13. The panel according to any one of claims 11-12, characterized in that the printing ink used for printing the decorative pattern (18) contains a solvent and is preferably a UV printing ink. 14. Panel according to claim 13, which differs in that the printing ink contains polymerizable acrylate and/or M-vinylcaprolactam. 15. The panel according to claim 14, which is characterized in that the printing ink used for printing the decorative pattern (18) contains polymerizable acrylate and M-vinylcaprolactam in an amount from 2 to 50 95 (wt.) by weight of the ink. 16. The panel according to any of the previous claims 11-15, characterized in that the printing ink and the polymer layer are subjected to joint curing by irradiation. 17. Panel according to any of the previous claims 11-16, characterized in that the decorative pattern (18) is applied by digital printing. 18. The panel according to any of the previous claims 11-17, which is characterized in that the PVC film has a thickness of 0.05 to 0.15 mm. 19. The panel according to any of the previous claims 11-18, which is characterized in that the plate (12) made of PVC has a thickness of 3 to 20 mm. 20. The panel according to any of the previous claims 11-19, which is characterized in that a layer containing a UV primer is provided on the PVC film (17). 21. The panel according to claim 20, which is characterized in that the layer containing the UV primer (14) has a surface mass of 1 to 15 g/m". 22. Panel according to any of the preceding claims 11-21, characterized in that the PVC plate (12) is a PVC plate produced by extrusion. 23. Panel according to any of the previous claims 11-22, characterized in that the PVC film (17) is thermally welded or is glued to the aforementioned plate. 24. The panel according to any of the preceding claims 11-23, which is characterized in that the polymer layer provides wear-resistant particles having an average diameter of 10 to 150 μm. 25. The panel according to claim 24, characterized in that the wear-resistant particles consist of corundum. 26. The panel according to any of the previous claims 11-25, which is characterized in that the main components of the polymer layer (19) are at least one of the following acrylates: 1,6-hexanediol diacrylate, polyetheretheracrylate, polyurethane acrylic acid ether and dipropylene glycol diacrylate. 27. The panel according to any of the previous claims 11-26, which is characterized in that, apart from the decorative pattern (18), no other decorative layers are used on the PVC film (17). 28. The panel according to any of the preceding claims 11-27, which is characterized in that the directly printed decorative pattern imitates the surface of natural wood, stone or tile. 29. The panel according to any of the preceding claims 11-28, characterized in that the plate (12) made of polyvinyl chloride does not contain a plasticizer. 30. The panel according to any of the preceding claims 11-29, characterized in that the polyvinyl chloride plate (12) consists of rigid PVC (NPVC). 31. The method of manufacturing the panel, which includes the following stages: - implementation of the method according to any of claims 1-10, where before heat treatment or after it, a PVC film with a thickness of 0.04 to 0.2 mm is applied to the PVC plate, 0) - printing the decorative pattern directly on the PVC film, - applying at least the first layer of polymer on the PVC film, and - curing the polymer layer. 32. The method according to claim 31, which is characterized by the fact that a second liquid polymer layer is applied to the still wet first polymer layer, and at the same time, the materials of these two polymer layers are partially mixed with each other and their joint hardening occurs, as a result of which the finally hardened polymer layer has a hardness gradient, such that the hardness of the coating decreases in depth from the surface of the finished coating. 33. The method according to any of the preceding claims 31 or 32, which is characterized by the fact that a heated calender is used to apply the PVC film in such a way that the PVC film is thermally welded to the carrier plate. 34. The method according to any of the previous claims 31-33, which is characterized by the fact that the decorative pattern is applied by digital printing directly on the PVC film. 35. The method according to any of the preceding claims 31-34, which is characterized in that the PVC film has a thickness of 0.05 to 0.15 mm. 36. The method according to any of the previous claims 31-35, which is characterized by the fact that the directly printed decorative pattern imitates the surface of natural wood, stone or tile covering. 37. The method according to any of the preceding claims 31-36, which is characterized by the fact that the plate (12) made of polyvinyl chloride does not contain a plasticizer. 38. 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